Tibial tubercle osteotomy for total knee arthoplasty and instruments and implants therefor

ABSTRACT

A method of performing a tibial tubercle osteotomy includes cutting a bone portion of a tibial tubercle from a remaining portion of the tibial tubercle, at least a portion of a patella ligament being attached to the bone portion. The bone portion of the tibial tubercle is separated from the remaining portion of the tibial tubercle such that the patella ligament remains attached to the bone portion. After completing a surgical procedure, the separated bone portion of the tibial tubercle is reattached to the remaining portion of the tibial tubercle.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] Not applicable.

BACKGROUND OF THE INVENTION

[0002] 1. The Field of the Invention

[0003] The present invention relates to methods and correspondinginstruments for gaining surgical access to the knee cavity by performinga tibial tubercle osteotomy as part of a minimally invasive total orpartial knee arthroplasty or other knee related surgery.

[0004] 2. Related Technology

[0005] As a result of accident, deterioration, or other causes, it isoften necessary to surgically replace all or portions of a knee joint.Joint replacement is referred to as arthroplasty. Conventional totalknee arthroplasty requires a relatively long incision that typicallyextends longitudinally along the lateral side of the leg spanning acrossthe knee joint. To allow the use of conventional techniques,instruments, and implants, the incision typically extends proximal ofthe knee and into the muscular tissue. In general, the longer theincision and the more muscular tissue that is cut, the longer it takesfor the patient to recover and the greater the potential for infection.

[0006] Accordingly, what is needed are minimally invasive procedures andcorresponding apparatus for accessing the knee joint to perform total orpartial knee arthroplasty.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Various embodiments of the present invention will now bediscussed with reference to the appended drawings. It is appreciatedthat these drawings depict only typical embodiments of the invention andare therefore not to be considered limiting of its scope.

[0008]FIG. 1 is an elevated front view of a leg in a bent position;

[0009]FIG. 2 is a elevated front view of a tibia of the leg shown inFIG. 1 with a portion of the tibial tuberosity removed;

[0010]FIG. 3 is an elevated side view of the tibia shown in FIG. 2;

[0011]FIG. 4 is a perspective view of a die cutter;

[0012]FIG. 5 is a perspective view of the arm assembly of the die cuttershown in FIG. 4;

[0013]FIG. 6 is an elevated front view of a guide;

[0014]FIG. 7 is a perspective view of the guide shown in FIG. 6; and

[0015]FIG. 8 is a top plan view of the guide shown in FIG. 6.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] The present invention relates to methods and correspondinginstruments for performing a tibial tubercle osteotomy to gain access tothe knee cavity as part of a minimally invasive total or partial kneearthroplasty or other knee related surgery. By way of example and not bylimitation, depicted in FIG. 1 is a knee 10 having an anterior side 12.Knee 10 is flexed to about 90 degrees. A transverse incision 14,approximately 10 cm long, is made mediolaterally through the skin layeracross the midline of knee 10 proximal of the tibial tuberosity. Asdepicted in FIG. 2, the tissue is retracted exposing in part a patellarligament 18 and a tibial tuberosity 20 of a tibia 22. A portion oftibial tuberosity 20 connected to patellar ligament 18 is now elevatedsuch that patellar ligament 18 remains connected thereto.

[0017] Specifically, FIG. 2 shows a lateral view of the proximal end oftibia 22. A distal portion 30 of tibial tuberosity 20 has been elevatedwhile a proximal portion 32 of tibial tuberosity 20 remains integralwith tibia 22. Patellar ligament 18 is excised from proximal portion 30of tibial tuberosity 20 so that the distal end of patellar ligament 18can be freely elevated in connection with distal portion 30 of tibialtuberosity 20. In one embodiment, distal portion 30 of tibial tuberosity20 is sized such that between about ⅓ to about ½ of the centralmediolateral width of patella ligament 18 and tibial tuberosity 20 isosteotimized from the proximal end of tibia 22. Thus about ⅓ to about ½of the distal contact surface of patellar ligament 18 remains connectedto distal portion 30 of tibial tuberosity 20.

[0018] Tibia 22 has an anterior cut surface 34. With reference to thelateral side view of tibia 22 depicted in FIG. 2, cut surface 34includes a proximally arched undercut portion 36 formed on the distalend of proximal portion 32 of tibial tuberosity 20. As a result of cutsurface 34, proximal portion 32 of tibial tuberosity 20 terminates at adistally projecting anterior ridge 42.

[0019] Cut surface 34 also includes a distally sloping portion 38extending from undercut portion 36 to an anterior border 40 of tibia 22.Cut surface 34 partially bounds a pocket 35 and has a transverseconfiguration taken along a plane extending proximal to distal that issimilar to a vertically bisected heart design as depicted onconventional playing cards. In contrast to forming a smooth bisectedheart shape design, cut surface 34 can also form a sharp or slightlyrounded inside angle that is typically 90° or less.

[0020] As depicted in FIG. 3, cut surface 34 also has a substantiallywedged shaped transverse configuration taken along a plane extendinganterior to posterior. Specifically, cut surface 34 comprises a lateralside 24 and an opposing medial side 26 that each slope inwardly so as tointersect at a vertical midline 28. In one embodiment, the inside angleθ between lateral side 24 and medial side 26 is in a range between about60° to about 120° with about 80° to about 100° being more preferred. Inalternative embodiments, cut surface 34 can be substantially flatextending mediolaterally or can form a rounded groove.

[0021] Elevated distal portion 30 of tibial tuberosity 20 has a cutsurface 46 that is complementary to cut surface 34. As will be discussedbelow in greater detail, one of the benefits of the configuration of cutsurfaces 34 and 46 is that once the procedure is complete, distalportion 30 of tibial tuberosity 20 is easily reinserted within pocket35. The complementary mating with undercut surface 36 helps lock distalportion 30 within pocket 35 as distal potion 30 is pulled proximal bypatellar ligament 18.

[0022] Distal portion 30 of tibial tuberosity 20 can be elevated using anumber of different techniques. By way of example and not by limitation,depicted in FIG. 4 is one embodiment of a die cutter 50 incorporatingfeatures of the present invention. Die cutter 50 comprises a housing 52having a substantially box shaped configuration. Housing 52 has a frontface 56 and an opposing back face 57 with side faces 58 and 60 extendingtherebetween. A top face 54 and an opposing bottom face 55 also extendbetween faces 56 and 57. Housing 52 bounds a chamber 62. Chamber 62communicates with the exterior through an elongated slot 64 formed onfront face 52 and an opening 66 formed on each side face 58 and 60.

[0023] A handle 68 outwardly projects from top face 54 of housing 52. Athreaded alignment bolt 69 passes through handle 68 and a portion ofhousing 52 so as to centrally project beyond front face 56 of housing52. Alignment bolt 69 threadedly engages with handle 68 and/or housing52 such that selective rotation of alignment bolt 69 facilitatesselective positioning of alignment bolt 69 beyond front face 56 ofhousing 52.

[0024] Partially disposed within chamber 62 of housing 52 are a pair oftranslating arms 70 and 72. As depicted in FIG. 5, each translating arm70 and 72 has a distal end 74 and an opposing proximal end 76. In oneembodiment of the present invention, means are provided for selectivelyadvancing at least one of the first and second translating arms 70, 72toward the other. By way of example and not by limitation, a shaft 78has threads formed along each end thereof with the threads beingoriented in opposing directions. Each translating arm 70 and 72 isthreaded onto a corresponding end of shaft 78. Accordingly, selectiverotation of shaft 78 causes translating arms 70, 72 to either movetogether or move apart. A socket 83 is formed on each end face of shaft78. Shaft 78 is selectively rotated by inselting a tool, such as a drillbit, through one of openings 66 (FIG. 4) of housing 52 and into socket83 of shaft 78. Rotation of the tool thus facilitates rotation of shaft78.

[0025] In alternative embodiments for the means for selectivelyadvancing, it is appreciated that shaft 78 can be replaced with avariety of other conventional threaded shaft or bolt mechanisms.Furthermore, shaft 78 can be replaced with elongated levered handles orother conventional apparatus that facilitate manual movement oftranslating arms 70 and 72. In yet other embodiments, it is appreciatedthat hydraulic, pneumatic, or electrical mechanisms can be used formovement of translating arms 70 and 72.

[0026] A plurality of spaced apart rails 79 outwardly project from eachside of each translating arm 70, 72. Rails 79 mesh with complementaryrails 92 formed on the interior of housing 52. The meshing of rails 79and 92 helps to ensure that translating arms 70, 72 are maintained inalignment during movement. Proper alignment of translating arms 70, 72is further maintained by a pin 75 slidably extending through each oftranslating arms 70, 72.

[0027] Returning to FIG. 4, distal end 74 of each translating arm 70, 72extends outside of chamber 62 through slot 64. Mounted at distal end 74of each translating arm 70 and 72 is an outwardly sloping head plate 80.Each head plate 80 has an interior face 81 with an undercut engagementslot 82 formed thereon. Each interior face 81 is disposed in acorresponding plane. The planes intersect so as to form an inside anglethat is substantially equal to the angle θ formed on cut surface 34.Slidably disposed within each slot 82 is a die 84. Each die 84 has abase 86 that is connected with a corresponding head plate 80 by beingslidably engaged within slot 82. As a result, dies 84 can be easilyreplaced with new dies or with dies having an alternative configuration.

[0028] A blade 88 outwardly projects from each base 86 so as to extendorthogonally from interior face 81 of the corresponding head plate 80.Each blade 88 terminates at a free sharpened edge 90. Each blade 88 andcorresponding sharpened edge 90 has a profile that is the sameconfiguration as the profile of cut surface 34 of tibial tuberosity 20previously discussed. Blades 88 are disposed so as to opposingly face atan intersecting angle. Accordingly, as shaft 78 is selectively rotated,translating arms 70, 72 move together causing sharpened edges 90 to matetogether.

[0029] During use, once tibial tuberosity 20 is exposed as discussedabove, die cutter 50 is positioned such that dies 84 are positioned onthe lateral and medial side of tibial tuberosity 20. The free end ofbolt 69 rests against the anterior surface of tibial tuberosity 20 andhelps to facilitate proper positioning of dies 84. In this regard, bolt69 functions as a spacer. In alternative embodiments, bolt 69 can bereplace with a variety of other mechanism that permit selective spacingadjustment. For example, a rod and clamp configuration can be used.

[0030] Once die cutter 50 is appropriately positioned, shaft 78 isselectively rotated, such as by the use of a drill, so that translatingarm 70 and 72 are advanced together. In so doing, the dies 84 penetratelaterally and medially into tibial tuberosity 20. Dies 84 continue toadvanced until distal portion 30 of tibial tuberosity 20 is separatedfrom proximal portion 32 thereof.

[0031] One of the benefits of using this process is that dies 84 producevery clean cut surfaces 34 and 46 with minimal bone loss. As a result,once the subsequent surgical procedure is completed, distal portion 30can be fit back into pocket 35 with a close tolerance fit. It isappreciated that a variety of alternative configurations of die cutterscan be used for selective die cutting of tibial tuberosity 20.

[0032] In contrast to die cutting tibial tuberosity 20, distal portion30 of tibial tuberosity 20 can also be elevated using a saw blade. Forexample, depicted in FIGS. 6-8 is a guide 100. Guide 100 comprises acentral plate 102 having a front face 104 and an opposing back face 106.Each of faces 104 and 106 extend between opposing sides 108 and 110.Extending between front face 104 and back face 106 are a plurality ofpassageways 112.

[0033] Formed on sides 108 and 110 of central plate 102 is a first sidehousing 114 and a second side housing 116, respectively. Each sidehousing 114 and 116 is formed so as to project beyond front face 104 ofcentral plate 102. Each of side housings 114 and 116 has an inside face118 and an opposing outside face 120. A cavity 122 extends through eachof side housings 114 and 116 between faces 118 and 120. Removablydisposed within cavity 122 of side housing 114 is a first template 124.A second template 126 is disposed within cavity 122 of side housing 116.Each template 124 and 126 has a substantially box-shaped configurationwhich includes an inside face 128 and an opposing outside face 130.Inside face 128 of templates 124 and 126 are each disposed in acorresponding plane. The planes intersect so as to form an inside anglethat is substantially equal to the angle θ formed on cut surface 34.

[0034] A guide slot 132 extends through each of templates 124 and 126between inside face 128 and outside face 130. Each guide slot 132 has aconfiguration complementary to the profile of cut surface 34 and extendsthrough templates 124 and 126 at an orientation perpendicular to insideface 128.

[0035] During use, once tibial tuberosity 20 is exposed, front face 104of central plate 102 is biased against the anterior side of tibialtuberosity 20 such that templates 124 and 126 are disposed on thelateral and medial side thereof. Guide slots 132 are aligned with distalportion 30 of tibial tuberosity 20 to be elevated. Once guide 100 isappropriately positioned, fasteners, such as screws, nails, or the like,are passed through passageways 112 and into tibia 22 so as to securelyretain guide 100 to tibia 22. It is noted that passageways 112 aresloped such that the fasteners extending therethrough extend intoportions of tibia 22 outside of distal portion 30 which is to beelevated.

[0036] Once guide 100 is positioned in place, a saw blade 140 is passedthrough guide slot 132 of template 124 from outside face 130 to insideface 128. Saw blade 140 is moved in a reciprocating manner so as topenetrate half way into tibial tuberosity 20. Once the reciprocating sawblade 140 has completed passage along guide slot 132, saw blade 140 ismoved over to template 126 and passed through the guide slot 132thereof. The process is then repeated. Once both cuttings are performed,distal portion 30 of tibial tuberosity 20 is freely removable from theremainder of tibia 22. The fasteners are then removed along with guide100. As with die cutters 50, it is appreciated that guide 100 can comein a variety of alternative configurations.

[0037] As previously mentioned, once distal portion 30 of tibialtuberosity 20 is elevated, patellar ligament 18 is retracted proximally,thereby exposing the knee joint. Once the knee joint is exposed, anynumber of knee related surgical procedures, such as total or partialknee arthroplasty, can be performed. Referring back to FIG. 2, uponcompletion of the surgical procedure, patellar ligament 18 is securedback in place by inserting distal portion 30 of tibial tuberosity 20back into pocket 35. As a result of undercut portion 36, distal portion30 of tibial tuberosity 20 is self-locking within pocket 35. If desired,however, various types of conventional bone anchors can be used tofurther secure distal portion 30 of tibial tuberosity 20 within pocket35.

[0038] The present invention may be embodied in other specific formswithout departing from its spirit or essential characteristics. Thedescribed embodiments are to be considered in all respects only asillustrative and not restrictive. The scope of the invention is,therefore, indicated by the appended claims rather than by the foregoingdescription. All changes which come within the meaning and range ofequivalency of the claims are to be embraced within their scope.

What is claimed is:
 1. A bone die cutter comprising: a housing having aninterior surface bounding a chamber, the housing having an opening incommunication with the chamber; a first translating arm having aproximal end and an opposing distal end, the first translating armpassing through the opening of the housing such that the proximal end isdisposed within the chamber of the housing and the distal end freelyextends beyond the housing; a second translating arm having a proximalend and an opposing distal end, the second translating arm passingthrough the opening of the housing such that the proximal end isdisposed within the chamber of the housing and the distal end freelyextends beyond the housing; a cutting die disposed on the distal end ofeach translating arm, the cutting dies having complementaryconfigurations and being opposing facing; and means for selectivelyadvancing at least one of the first and second translating arms towardthe other.
 2. A bone die cutter as recited in claim 1, wherein each diecomprises a blade that terminates at a sharpened edge, the sharpenededge having a contour that corresponds substantially to the contour ofthe exterior surface of a vertically bisected heart design.
 3. A bonedie cutter as recited in claim 1, wherein each die comprises anoutwardly projecting blade, the dies being positioned so that the bladesintersect at an angle when the blades are brought together.
 4. A bonedie cutter as recited in claim 1, further comprising a spacer adjustablymounted to the housing and projecting between the first and secondtranslating arms.
 5. A bone die cutter as recited in claim 4, whereinthe spacer comprises a bolt in threaded engagement with the housing. 6.A bone die cutter as recited in claim 1, wherein each translating armhas a distal end face, each cutting die being removably mounted to thedistal end face of a corresponding translating arm.
 7. A bone die cutteras recited in claim 6, wherein the distal end face of each translatingarm is disposed in a discrete corresponding plane, the planesintersecting so as to form an inside angle in a range between about 60°to about 120°.
 8. A bone die cutter as recited in claim 1, wherein themeans for selectively advancing comprises a threaded shaft, the proximalend of the first and second translating arms being mounted on the shaft,selective rotation of the shaft causing at least one of the first andsecond translating arms to advance toward the other.
 9. A bone diecutter comprising: a housing comprising a first rail and a second rail;a first translating arm having a proximal end and an opposing distalend, the first translating arm being mounted on the housing in slidableengagement with the first rail so that the distal end of the firsttranslating arm projects away from the housing; a second translating armhaving a proximal end and an opposing distal end, the second translatingarm being mounted on the housing in slidable engagement with the secondrail so that the distal end of the second translating arm projects awayfrom the housing; a first die being mounted on the distal end of thefirst translating arm, the first die comprising a first outwardlyprojecting blade; a second die being mounted on the distal end of thesecond translating arm, the second die comprising a second outwardlyprojecting blade, the first and second rails being configured to guidethe first and second translating arms toward each other so that thefirst and second blades draw together.
 10. A bone die cutter as recitedin claim 9, wherein the housing comprises an interior surface bounding achamber, the housing having an opening in communication with thechamber, the proximal end of the first and second translating arms beingdisposed within the chamber of the housing.
 11. A bone die cutter asrecited in claim 9, wherein each blade terminates at a sharpened edge,the sharpened edge having a contour that corresponds substantially tothe contour of the exterior surface of a vertically bisected heartdesign.
 12. A bone die cutter as recited in claim 9, wherein each diecomprises an outwardly projecting blade, the dies being positioned sothat the blades intersect at an angle when the blades are broughttogether.
 13. A bone die cutter as recited in claim 9, furthercomprising a spacer adjustably mounted to the housing and projectingbetween the first and second translating arms.
 14. A bone die cutter asrecited in claim 9, further comprising means for selectively advancingat least one of the first and second translating arms toward the other.15. A bone die cutter as recited in claim 14, wherein the means forselectively advancing comprises a threaded shaft, the proximal end ofthe first and second translating arms being mounted on the threadedshaft such that selective rotation of the shaft causes at least one ofthe first and second translating arms to advance toward the other.
 16. Amethod of cutting bone with a bone die cutter, the method comprising:positioning complementary cutting dies on at least substantiallyopposing sides of a bone; pressing at least one of the cutting diestoward the other so that the cutting dies cut a bone portion from thebone; separating the cut bone portion from the bone; and reattaching thecut bone portion to the bone.
 17. A method as recited in claim 16,wherein the act of separating the cut bone portion forms a recessedpocket on the bone, the cut bone portion being reattached into therecessed pocket.
 18. A method as recited in claim 16, further comprisingthe act of performing a surgical procedure between the acts ofseparating and reattaching.
 19. A method as recited in claim 16, whereinthe bone comprises a tibial tubercle.
 20. A method as recited in claim16, wherein each of the dies has a blade projecting therefrom, the actof positioning the complementary cutting dies comprising positioning thedies so that the blades intersect at an angle when the blades arebrought together.
 21. A method of performing a tibial tubercle osteotomycomprising: cutting a bone portion of a tibial tubercle from a remainingportion of the tibial tubercle, at least a portion of a patella ligamentbeing attached to the bone portion; separating the bone portion of thetibial tubercle from the remaining portion of the tibial tubercle suchthat the patella ligament remains attached to the bone portion; andreattaching the separated bone portion of the tibial tubercle to theremaining portion of the tibial tubercle.
 22. A method as recited inclaim 21, wherein the act of cutting the bone portion comprisesmediolaterally cutting through the tibial tubercle.
 23. A method asrecited in claim 21, wherein the act of cutting the bone portioncomprises compressing complementary cutting dies on opposing sides ofthe tibial tubercle.
 24. A method as recited in claim 21, wherein theact of cutting the bone portion comprises passing a saw blade throughthe tibial tubercle.
 25. A method as recited in claim 21, wherein thetibial tubercle has a proximal end and an opposing distal end, the boneportion being separated from the remaining portion such that a recessedpocket is formed on the tibial tubercle, the recessed pocket having anundercut surface extending toward the proximal end of the tibialtubercle.
 26. A method as recited in claim 25, wherein the recessedpocket has a longitudinal cross sectional contour that correspondssubstantially to the contour of an exterior surface of a verticallybisected heart design.
 27. A method as recited in claim 21, wherein thebone portion is separated from the remaining portion such that arecessed pocket is formed on the tibial tubercle, the act of reattachingthe separated bone portion comprising inserting the bone portion backinto the pocket.